Cable systems and cable-type roof bolts have been used in the mining industry to reinforce the mine roof and prevent its collapse. Cable systems generally include a shank formed of a multi-strand cable and a barrel and wedge assembly secured to the cable to provide the necessary support after tensioning or support the bearing plate of the mine roof bolt assembly. The barrel and wedge assembly includes a tubular barrel with a plurality of locking wedges positioned within the barrel surrounding the cable securing the barrel and wedge assembly to the cable.
Cable mine roof bolts have been utilized in resin grouted applications. In resin grouted applications, the mine roof bolt is rotated to mix the resin during installation. Examples of cable mine roof bolts designed for resin grouted applications can be found in U.S. Pat. Nos. 5,230,589; 5,219,703 and 5,375,946.
To further support the mine roof a steel cable may be connect to the mining bolts to support the rock between the bolting sites. Various types of cabling systems have been introduced. One example is a cable bolting system that consists of a cable which is positioned into a bore hole. Bonding material is then pumped in under pressure around the cable to secure it to the rock. The bonding material must be pumped externally in a separate step after the cable is within the bore hole. The bonding material must completely fill the bore hole in order to ensure proper contact between the rock and the cable.
A further design for a cable-type mining support is made by Arnall, Inc. Arnall manufactures a stranded cable a length of which has an open-weave arrangement. (i.e., the strands are not tightly wound). This allows a bonding agent of cementatious grout, which is pumped into a bore hole, to penetrate into and integrate with the cable.
The pumping of viscous liquid grout presents challenges that are not easily resolved by the prior art grouted cable mine roof bolts. For example, the grouts used for reinforcing cable type roof bolts are generally fast-setting grouts, which can begin to block flow of grout in the roof bore hole shortly after being injected into the bore hole. In addition, lateral cracks or capillaries in the mine roof adjacent the lower rock strata may divert the pressurized fluidized grout away from the upper column of the cable bore hole, leaving a gap between the lower grouted column and the anchored wedge portion of the mine roof bolt. In many applications, the pressurization of the grout into the cable bore hole is all that is available for controlling the penetration of the grout, particularly to the upper portions of the annular column in which the cable is suspended.
What is needed is a method for distributing fluidized grout upwards in a vertical column that allows control of the fluid grout penetration into the full vertical column.